U.S. patent application number 13/922451 was filed with the patent office on 2013-12-26 for hearing aid comprising a feedback alram.
The applicant listed for this patent is OTICON A/S. Invention is credited to Graham NAYLOR.
Application Number | 20130343587 13/922451 |
Document ID | / |
Family ID | 46456355 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130343587 |
Kind Code |
A1 |
NAYLOR; Graham |
December 26, 2013 |
HEARING AID COMPRISING A FEEDBACK ALRAM
Abstract
A hearing aid comprises a microphone configured to receive an
acoustic input signal and convert the signal into an electric input
signal, an audiological signal processing unit coupled to the
microphone and configured to process the electric input signal to a
processed signal, an amplifier coupled to the audiological signal
processing unit and configured to amplify the processed signal to
an amplified signal, and a receiver coupled to the amplifier and
configured to transform the amplified signal into an acoustic
output signal. The hearing aid further comprises a howl detector
coupled to the signal processing unit and configured to detect the
presence of a feedback howl originating from the hearing aid an
analyzer coupled to the howl detector and configured to determine a
value indicative of whether the feedback howl detected is
potentially audible to a person neighbouring the user of the
hearing aid.
Inventors: |
NAYLOR; Graham; (Smorum,
DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OTICON A/S |
Smorum |
|
DK |
|
|
Family ID: |
46456355 |
Appl. No.: |
13/922451 |
Filed: |
June 20, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61662391 |
Jun 21, 2012 |
|
|
|
Current U.S.
Class: |
381/318 |
Current CPC
Class: |
H04R 25/45 20130101;
H04R 25/453 20130101; H04R 25/305 20130101 |
Class at
Publication: |
381/318 |
International
Class: |
H04R 25/00 20060101
H04R025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2012 |
EP |
12172959.4 |
Claims
1. Hearing aid comprising a microphone configured to receive an
acoustic input signal and to convert the acoustic input signal into
an electric input signal, an audiological signal processing unit
coupled to the microphone and being configured to process the
electric input signal to a processed signal, an amplifier coupled
to the audiological signal processing unit and being configured to
amplify the processed signal to an amplified signal, and a receiver
coupled to the amplifier and being configured to transform the
amplified signal into an acoustic output signal, a howl detector
coupled to the signal processing unit and being configured to
detect the presence of a feedback howl originating from the hearing
aid an analyzer coupled to the howl detector and being configured
to determine a first value indicative of whether or not the
feedback howl detected is potentially audible to a person
neighbouring the user of the hearing aid, a trigger unit
operatively connected to the analyzer and being configured to
trigger a corrective action considering the first value.
2. Hearing aid according to claim 1, wherein the analyzer is
further configured to determine a second value indicative of
whether or not the feedback howl detected is potentially inaudible
to the hearing aid user.
3. Hearing aid (100) according to claim 1, wherein the hearing aid
comprises a discriminator configured to create an impact value
indicative of whether or not the feedback howl detected persists
over a significant period of time.
4. Hearing aid according to claim 1, wherein the howl detector is
configured to detect a frequency and/or an amplitude and/or a
duration of the feedback howl detected.
5. Hearing aid according to claim 1 comprising a memory and
configured to store one or more of the characteristics of a number
of howl-events in the memory, including one or more of a centre
frequency, a corresponding amplitude, and a duration in time.
6. Hearing aid according to claim 2 wherein the trigger unit is
configured to further trigger the corrective action according to
the second value, and/or the impact value, and/or said
characteristics of a number of howl-events.
7. Hearing aid according to claim 1 wherein the first value
indicative of whether or not the feedback howl detected is
potentially audible to a person neighbouring the user of the
hearing aid comprises an estimate of the sound pressure level
SPL.sub.howl from a howl in the hearing aid worn by the user at a
distance DIST within the user's nearest environment.
8. Hearing aid according to claim 1, wherein the hearing aid
further comprises a signaller operatively coupled both the trigger
unit and the receiver and being configured to present to the
receiver an electric signal transformable to an acoustic sound
perceivable by the user.
9. Hearing aid according to claim 8, wherein the electric signal
presented to the receiver is, as a first corrective action, a
pre-stored and/or on-demand generated warning signal.
10. Hearing aid according to claim 1, wherein the hearing aid
further comprises an attenuator operatively coupled to the trigger
unit and being configured, as a second corrective action, to
attenuate the amplified signal presented to the receiver.
11. Hearing aid according to claim 1 comprising a voice activity
detector.
12. Hearing aid according to claim 11 configured to log whether the
voice of a human being has been detected by the hearing aid within
a predefined time interval from the current time, and to use such
information to influence a possible corrective action.
13. Hearing aid according to claim 1, wherein the electric signal
presented to the receiver comprises, as a third corrective action,
a substitute signal representing an acoustic input signal of a
hearing aid component distinct from the hearing aid.
14. Hearing aid according to claim 13, wherein the substitute
signal at least partially substitutes the amplified signal and/or
the processed signal.
15. A hearing aid system comprising a hearing aid according to
claim 1 AND an auxiliary device.
16. A hearing aid system according to claim 15 wherein the
auxiliary device comprises a Smartphone.
17. Method for operating a hearing aid comprising the steps:
receiving an acoustic input signal and converting the acoustic
input signal into an electric input signal and processing the
electric input signal to a processed signal detecting the presence
of a feedback howl originating from the hearing aid, preferably
using the processed signal and/or control signals from an
audiological signal processing unit comprised by the hearing aid
determining a first value indicative of whether or not the feedback
howl detected is potentially audible to a person neighbouring the
user of the hearing aid triggering a corrective action considering
the first value.
18. Method according to claim 17, comprising the step: presenting
to the receiver, as a first corrective action, a pre-stored and/or
on-demand generated warning signal that is transformable to an
acoustic sound perceivable by the user.
19. Method according to claim 17, wherein the corrective action
comprises playing a warning message to the user via an output
transducer, where the warning signal is appropriately adapted in
frequency and gain to allow the user to perceive the message
conveyed by the warning signal considering the user's hearing
ability.
20. Method according to claim 17, comprising the step: attenuating,
as a second corrective action, the amplified signal presented to
the receiver.
21. Method according to claim 17, comprising the step: presenting
to the receiver, as a third corrective action, a substitute signal
representing an acoustic input signal of a hearing aid component
distinct from the hearing aid.
22. Computer program for operating a hearing aid, the computer
program comprising program code means for causing the hearing aid
to carry out the steps of the method as defined in claim 17, when
the computer program is run on a computer controlling the hearing
aid.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a hearing aid. The present
disclosure furthermore relates to a corresponding operating method
of operating a hearing aid and to a corresponding computer
program.
BACKGROUND OF THE INVENTION
[0002] It is often observed that a hearing-aid user's hearing aid
whistles or howls for a significant period of time, and so loudly
that people around the user can hear it. Such whistling or howling
results from inadequate feedback cancellation capabilities of prior
art hearing aids, often leaving only manual user actions (e.g.
re-positioning of the aid, or reducing gain/volume) to rectify the
situation. Since the undesired feedback is inaudible for the user,
action is not taken until someone else draws the user's attention
to the problem. This causes embarrassing situations for friends,
family, bystanders, and usually for the users themselves.
[0003] WO 2011/026113 A1 discloses a method and system for
informing a user about hearing aid feedback noise including, for
example, receiving, through one or more microphones, an acoustic
signal sample, analyzing the acoustic signal sample to determine
whether feedback noise is present in the acoustic signal sample,
and displaying to the user an indication of whether feedback noise
is present in the acoustic signal sample.
DESCRIPTION OF THE INVENTION
[0004] It is an object of the present disclosure to provide a
hearing aid that can be operated less conspicuously.
[0005] A hearing Aid:
[0006] Regarding the hearing aid the object is achieved by a
hearing aid comprising a howl detector coupled to the signal
processing unit and being configured to detect the presence of a
feedback howl originating from the hearing aid, an analyzer coupled
to the howl detector and being configured to determine a first
value indicative of whether or not the feedback howl detected is
potentially audible to a person neighbouring the user of the
hearing aid, and a trigger unit operatively connected to the
analyzer and being configured to trigger a corrective action
considering the first value.
[0007] The term `a person neighbouring the user of the hearing aid`
is in the present context taken to mean a person that is within
hearing distance of a howl created by the hearing aid. Such
neighbouring person may e.g. be taken to be within 3 m of the user,
such as within 2 m or 1 m of the user wearing the hearing aid
creating the howl.
[0008] A corrective action in the sense of the present disclosure
is an action performed by the hearing aid automatically, e.g. such
as attenuating the amplified signal presented to the receiver,
informing the user, etc. A corrective action can e.g. comprise
playing a warning signal for the user (via a signal perceived by
the user as an acoustic signal, e.g. via a speaker unit). Such
corrective action may e.g. comprise playing a warning message to
the user via an output transducer (e.g. speaker unit), where the
warning signal is appropriately adapted in frequency and gain to
allow the user to perceive the message conveyed by the warning
signal (considering the user's hearing ability, e.g. impairment). A
corrective action may additionally or alternatively include
communicating a warning to the user by a visual indication or by a
mechanical (vibration) indication. A corrective action can inform
the user to preferably perform a manual user action.
[0009] The fact that the trigger unit triggers a corrective action
considering the first value does not necessarily mean that the
triggering is performed using the first value exclusively. Instead
the first value may be further processed or weighted using other
values and afterwards fed to the trigger unit.
[0010] In an embodiment, the hearing aid is adapted to provide a
frequency dependent gain to compensate for a hearing loss of the
user. Various aspects of digital hearing aids are described in
[Schaub; 2008] (Arthur Schaub, Digital hearing Aids, Thieme
Medical. Pub., 2008).
[0011] The hearing aid of the present disclosure combines the
detection of a feedback howl with the assessment whether or not the
feedback howl is potentially audible to a person neighbouring the
user of the hearing aid. The present disclosure includes the
recognition that it is not necessary to initiate a corrective
action for every feedback howl, but only for those potentially
leading to embarrassing situations for the hearing aid user.
[0012] Thus, the disclosure presents a better solution than
previously known solutions because it reduces the incidence of
embarrassing situations for the hearing aid user and his/her family
and acquaintances.
[0013] In order to detect a feedback howl, the howl detector can
comprise calculation means configured to perform e.g. a FFT on the
processed signal transmitted to the howl detector by the
audiological signal processing unit. Preferably, the howl detector
is configured to determine the frequency and/or amplitude of a
howl. Advantageously the howl detector is configured to detect
and/or transmit a frequency and/or an amplitude (and/or a duration)
of the feedback howl detected to the analyzer. In an embodiment,
the hearing aid comprises a memory and is adapted to store one or
more of the characteristics of a howl-event in the memory. In an
embodiment such characteristics include a centre frequency, a
corresponding amplitude, and a duration in time. In an embodiment,
characteristics of a number of howl events are stored in the
memory. Thereby an indication of the character of the howl event(s)
can be extracted, e.g. as indicated by a frequency of howl-events.
In an embodiment, such information is used as an input to the
analyzer and/or the discriminator to influence a possible
corrective action. Howl detection in hearing aids is e.g. described
in EP 1 718 110 A1.
[0014] In the present context howl due to acoustic feedback is
taken to refer to narrow-band frequency components that are
distinct in the wide band acoustic signal. In an embodiment, howl
is assumed, when a peak is detected in the input signal picked up
by the microphone of the hearing aid and where the peek is NOT
assumed to form part of the target input signal. In an embodiment,
a howl feedback component is assumed to comprise a signal component
above a predefined minimum level, e.g. 30 dB SPL. In an embodiment,
a feedback component is assumed to comprise a signal component in a
relatively narrow frequency range, e.g. less than 40 Hz.
[0015] In an embodiment, the hearing aid comprises a level detector
for determining the level of an input signal (e.g. a speech signal)
and/or a howl (e.g. on a band level and/or of the full (wide band)
signal). The input level of the electric microphone signal picked
up from the user's acoustic environment is e.g. a classifier of the
environment. In an embodiment, the level detector is adapted to
classify a current acoustic environment of the user according to a
number of different (e.g. average) signal levels. The level of the
howl may be used as an input to the discriminator (indicating the
severity of the event).
[0016] In an embodiment, the first value indicative of whether or
not the feedback howl detected is potentially audible to a person
neighbouring the user of the hearing aid comprises an estimate of
the sound pressure level SPL.sub.howl from a howl in the hearing
aid worn by the user at a distance DIST within the user's nearest
environment. In order to calculate whether or not the feedback howl
is potentially audible to a person neighbouring the user of the
hearing aid, the analyzer can be configured to estimate from the
amplitude of the howl (and/or hearing aid characteristics) a sound
pressure level of the feedback howl occurring at a typical distance
between the hearing aid and a bystander. Such a typical distance
can be, for example, 80 cm. If a sound pressure level of the
detected howl at the typical distance is, for example, less than 10
dB SPL, the howl is unlikely to be audible to a bystander. A
criterion for taking a corrective action may thus be expressed as
SPL.sub.howl(DIST)>SPL.sub.max,acc, where SPL.sub.howl(DIST) is
the estimated sound pressure level from a howl in the hearing aid
worn by the user at a distance DIST within the user's nearest
environment, and SPL.sub.max,acc is the maximum acceptable sound
pressure level at a bystander's location. In an embodiment, DIST is
smaller than 3 m, such as smaller than 2 m, such as smaller than 1
m. In an embodiment, SPL.sub.max,acc is larger than 6 dB (SPL),
such as larger than 10 dB (SPL), such as larger than 20 dB (SPL).
SPL.sub.howl(DIST) may e.g. be determined for a given howl incident
from the measured level of the current howl. It may e.g. be read
from a predefined table stored in a memory of the hearing aid, the
table listing measured howl level in the hearing aid and estimated
howl level at various distances from the user wearing the hearing
aid. Alternatively, it may be determined in the hearing aid from
the current howl level and a specific distance, e.g. a maximum
distance of interest, e.g. by free field calculations. It is to be
understood that the analyzer can be configured to weigh the sound
pressure level using e.g. the frequency of the howl (or its level
or its duration). Furthermore other psychoacoustic values known to
the skilled person can be implemented in the analyzer in order to
determine whether or not the feedback howl is potentially audible
to a person neighbouring the user of the hearing aid. In an
embodiment, the hearing aid (e.g. the analyzer) is adapted to log
(recent) events related to the environment of the user. In an
embodiment, the hearing aid (e.g. the analyzer) is adapted to log
whether the voice of a human being has been detected by the hearing
aid within a predefined time interval from the current time. In an
embodiment, such information is used (e.g. to the discriminator or
the trigger unit) to influence a possible corrective action. In
case no recent events of voice-detection in the user's environment
has occurred, the need for corrective action (to please the
environment) may be less than if one or more recent of
voice-detection-events has been registered. In an embodiment, the
analyzer is adapted to cyclically log the point in time (and
possibly duration and/or the average level, e.g. the average power
spectral density, PSD) of the most recent voice-detection-events,
e.g. within the last 60 s (1 minute), or within the last 300 s (5
minutes).
[0017] In a particular embodiment, the hearing aid comprises a
voice activity detector for determining whether or not an input
signal comprises a voice signal (at a given point in time). A voice
signal is in the present context taken to include a speech signal
from a human being. It may also include other forms of utterances
generated by the human speech system (e.g. singing). In an
embodiment, the voice detector is adapted to classify a current
acoustic environment of the user as a VOICE or NO-VOICE
environment. In an embodiment, the hearing aid comprises a memory,
wherein the most recent occurrences of voice detection are stored
(possibly together with a level indication of the detected voice).
This allows an estimate of the time elapsed from the last
occurrence (or a number of the last occurrences) of voice detection
to the current time, whereby an indication of the current acoustic
environment of the user is provided. Voice detection in hearing
aids is e.g. dealt with in WO 91/03042 A1.
[0018] The first value calculated by the analyzer can be a simple
signal, flagging periods of time in which a feedback howl
originating from the hearing aid is potentially audible to a person
neighbouring the user of the hearing aid. The first value
calculated by the analyzer can also be multi-valued.
[0019] In a preferred embodiment the analyzer is further configured
to determine a second value indicative of whether or not the
feedback howl detected is potentially inaudible to the hearing aid
user. The present disclosure also includes the recognition that a
feedback howl is not necessarily audible for the user of the
hearing aid and the information about an occurring howl has to be
made accessible to the user differently, e.g. depending on the
hearing impairment of the user. To determine that, the amplitude
and/or frequency of a feedback howl can be compared by the analyzer
to an individual hearing profile of a user (e.g. an audiogram for
the ear at which the hearing aid is worn) that may be stored in the
hearing aid. If, for example, the howl detected is potentially
inaudible to the hearing aid user, the analyzer could raise a flag
indicating that, e.g. by delivering an information signal to the
user in a frequency range (and gain) where he/she is able to
perceive the information.
[0020] In a further preferred embodiment, the hearing aid comprises
a discriminator configured to create an impact value indicative of
whether or not the feedback howl detected persists over a
significant period of time. Thereby it can be achieved that a
corrective action is not initiated for short-lived feedback howl,
thus avoiding unnecessary interference in the normal operation of
the hearing aid. In the simplest case, a significant period of time
can be a predetermined time period stored in the hearing aid, e.g.
1500 ms. A feedback howl occurring for a period of time less than
this predetermined time period would be assigned a low impact
value, e.g. in the simplest case a zero-flag.
[0021] In a preferred embodiment the trigger unit is configured to
further trigger the corrective action according to the second value
and/or the impact value. This means that a corrective action may
not only be triggered dependent on whether the howl detected is
potentially audible to a person neighbouring the user of the
hearing aid, as indicated by the first value, but also whether the
howl detected e.g. persists over a significant period of time, as
indicated by the impact values or whether the howl detected is
potentially inaudible to the hearing aid user, as indicated by the
second value.
[0022] Naturally, the manner in which the first, second and impact
values are combined/merged in order for the trigger unit to trigger
a corrective action will depend on the specific use case. In an
embodiment, a weighting of the values is implemented in dependence
of the user (e.g. of the user's hearing impairment).
[0023] In a preferred embodiment the hearing aid comprises a
signaller operatively coupled to both the trigger unit and the
receiver. The signaller can be configured to present to the
receiver an electric signal transformable to an acoustic sound
perceivable by the user (e.g. an information signal). Alternatively
or additionally, the signaller can be configured to create an
information signal perceivable by the user as a vibration (e.g. of
a particular pattern indicating a particular information), e.g. a
vibration of the hearing aid. In an embodiment, the hearing aid
comprises a wireless interface to an auxiliary device, allowing the
signaller to create an information signal, which is transmitted to
an auxiliary device, e.g. a cellular telephone (e.g. transmitted as
an SMS), or a remote control (or a contra-lateral hearing aid of a
binaural fitting), for indication to the user via said device, e.g.
via a light indicator, e.g. an LED or a display, via a speaker
and/or a vibration of the auxiliary device. In an embodiment, the
auxiliary device is a Smartphone, configured to receive the
information signal and to transfer the information to a user of the
Smartphone, e.g. by a text message or by a graphic illustration or
a combination thereof on a display of the Smartphone.
[0024] The electric signal presented to the receiver can be a
pre-stored and/or on-demand generated warning signal. Presenting
such warning signal to a user can be a first corrective action.
This is especially suitable if the feedback howl, as indicated by
the second value, is inaudible to the hearing aid user. In this
case the user is informed via the warning signal.
[0025] The hearing aid can comprise an attenuator operatively
coupled to the trigger unit and being configured to attenuate the
amplified signal presented to the receiver. Such attenuation can be
a second corrective action resulting in the feedback howl to
vanish. Attenuation can be performed partially or totally,
preferably solely in a frequency band surrounding the feedback
howl.
[0026] In an embodiment, the hearing aid comprises an acoustic
(and/or mechanical) feedback suppression system. In an embodiment,
feedback cancellation (or at least reduction) is implemented by
subtracting an estimate of the feedback signal within the hearing
aid from the input signal. Preferably, the feedback cancellation
system comprises an adaptive filter allowing to track feedback path
changes over time. The adaptive filter comprises a linear time
invariant filter to estimate the feedback path, which has its
filter weights updated over time with a certain update or
adaptation rate [Engebretson, 1993] (A. Engebretson, M. French-St.
George, "Properties of an adaptive feedback equalization
algorithm", J. Rehabil. Res. Dev., 30(1), pp. 8-16, 1993). The
filter updates are e.g. calculated using stochastic gradient
algorithms, including some form of the Least Mean Square (LMS) or
the Normalized LMS (NLMS) algorithms. Thereby the error signal (the
feedback corrected input signal) is minimized in the mean square
sense. Various aspects of adaptive filters are e.g. described in
[Haykin] (S. Haykin, Adaptive filter theory (Fourth Edition),
Prentice Hall, 2001).
[0027] In an embodiment, the hearing aid comprises an antenna and
transceiver circuitry for wirelessly receiving an electric input
signal from another device, e.g. a communication device, a remote
control or another hearing aid.
[0028] In a further embodiment, to enable the hearing aid for a
third corrective action, the electric signal presented to the
receiver is a substitute signal. The substitute signal can
represent an acoustic input signal of a hearing aid component
distinct from the hearing aid.
[0029] If, for example, the hearing aid and the hearing aid
component distinct from the hearing aid form a binaural hearing aid
system, a feedback howl occurring in either one of the two
components can be substituted using a substitute signal from the
respective other component. This is a quite acceptable measure for
as long the feedback howl persists. The substitute signal can at
least partially substitute the amplified signal and/or the
processed signal.
[0030] In a preferred embodiment, to further increase the hearing
comfort while a feedback howl occurs, the frequency band of the
substitute signal includes merely the frequency band of the
feedback howl detected.
[0031] It is to be understood that the three corrective actions
described above can be combined arbitrarily. If, for example, the
attenuator attenuates the amplified signal presented to the
receiver, which also means less auditory information for the
hearing aid user, it is suitable that the signaller is configured
to signal a warning signal to the hearing aid user giving him/her
the chance to react promptly.
[0032] It is to be understood that, as modern hearing aid include
versatile processing means, the functionality of functional
components, e.g. the howl detector, the analyzer and so forth can
be realized in one of the same processing means.
[0033] A hearing Aid System:
[0034] In a further aspect, a hearing aid system comprising a
hearing aid as described above, in the `detailed description of
embodiments`, and in the claims, AND an auxiliary device is
moreover provided.
[0035] In an embodiment, the system is adapted to establish a
communication link between the hearing aid and the auxiliary device
to provide that information (e.g. control and status signals,
possibly audio signals) can be exchanged or forwarded from one to
the other.
[0036] In an embodiment, the auxiliary device is or comprises an
audio gateway device adapted for receiving a multitude of audio
signals (e.g. from an entertainment device, e.g. a TV or a music
player, a telephone apparatus, e.g. a mobile telephone (e.g. a
Smartphone) or a computer, e.g. a PC) and adapted for allowing the
selection and/or combination of an appropriate one of the received
audio signals (or combination of signals) for transmission to the
hearing aid. In an embodiment, the auxiliary device is or comprises
a remote control for controlling functionality and operation of the
hearing aid(s). In an embodiment, the auxiliary device is or
comprises a Smartphone.
[0037] In an embodiment, the auxiliary device is another hearing
aid. In an embodiment, the system comprises two hearing aids
adapted to implement a binaural hearing aid system.
[0038] In an embodiment, the auxiliary device is adapted to detect
the howl of the hearing aid and to transmit an information signal
to the hearing aid in case howl is detected from the hearing aid in
question. Such auxiliary device(s) may e.g. be located in a room,
where the user is expected to be present, e.g. in a living room or
an auditorium, e.g. a class room).
[0039] A Method:
[0040] Regarding the operating method of operating a hearing aid
the object is achieved by operating a hearing aid with the steps
of: [0041] receiving an acoustic input signal and converting the
signal into an electric input signal and processing the electric
input signal to a processed signal [0042] detecting the presence of
a feedback howl originating from the hearing aid, preferably using
the processed signal and/or control signals from an audiological
signal processing unit comprised by the hearing aid [0043]
determining a first value indicative of whether or not the feedback
howl detected is potentially audible to a person neighbouring the
user of the hearing aid [0044] triggering a corrective action
according to the first value.
[0045] Principally the operating method of the present disclosure
shares the advantages of the hearing aid of the present disclosure.
In particular, the operating method has preferred embodiments that
correspond to additional features of the embodiments of the hearing
aid described above. For instance, in a preferred embodiment, the
method comprises the step of presenting to the receiver, as a first
corrective action, a pre-stored and/or on-demand generated warning
signal that is transformable to an acoustic sound perceivable by
the user.
[0046] In a further preferred embodiment the method comprises the
step of attenuating, as a second corrective action, the amplified
signal presented to the receiver.
[0047] Alternatively or additionally the operating method can
comprise the step of presenting to the receiver, as a third
corrective action, a substitute signal representing an acoustic
input signal of a hearing aid component distinct from the hearing
aid.
[0048] A Computer Program:
[0049] Regarding the computer program, the above identified object
is achieved by a computer program for operating a hearing aid, the
computer program comprising program code means for causing the
hearing aid to carry out the steps of the operating method as
described above, when the computer program is run on a computer
controlling the hearing aid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] These and other aspects of the disclosure will be apparent
from and elucidated with reference to the embodiments described
hereinafter.
[0051] In the following drawings:
[0052] FIG. 1 shows schematically and exemplary an embodiment of a
hearing aid in accordance with the disclosure,
[0053] FIG. 2 shows exemplary a flow chart illustrating an
embodiment of an operating method in accordance with the
disclosure,
[0054] FIG. 3 schematically shows a hearing aid according to the
present disclosure.
DESCRIPTION OF THE EMBODIMENTS
[0055] As a conventional hearing aid, the hearing aid 100 in FIG. 1
comprises a microphone (Mic.) 1 configured to receive an acoustic
input signal 11 and to convert the acoustic input signal 11 into an
electric input signal 12, an audiological signal processing unit
(Pre-processing) 8 coupled to the microphone 1 and being configured
to process the electric input signal 12 to a processed signal 18,
an amplifier (Amplifier) 9 coupled to the audio-logical signal
processing unit 8 and being configured to amplify the processed
signal 18 to an amplified signal 19 and a receiver (Loudspeaker) 10
coupled to the amplifier 9 and being configured to transform the
amplified signal 19 into an acoustic output signal 20.
[0056] Depicted branching off from the signal processing unit 8 is
a howl detector (Howl detector) 2, which is configured to detect
the presence of a feedback howl and to determine frequency and
amplitude (and possibly duration) of the howl. As can be seen from
FIG. 1, the processed signal 18 originating from the audiological
signal processing unit 8 is fed to the howl detector 2 as an input
signal. This signal may be the electric input signal 12 directly or
a processed version thereof (e.g. a feedback corrected version, in
case the hearing aid comprises a feedback cancellation system). In
an embodiment, the amplified signal 19 may alternatively or
additionally be fed to the howl detector 2. Optionally other
control signals 18', indicated by the dotted arrow, can be fed to
the howl detector for the detection of a howl.
[0057] If a howl is detected, a signal 21 representing the
frequency and/or the amplitude of the howl is transmitted to an
analyzer (Analyzer) 3, which is coupled to the howl detector 2. The
analyzer 3 is configured to determine a first value 23 indicative
of whether or not the feedback howl detected is potentially audible
to a person neighbouring the user of the hearing aid 100. In this
embodiment the first value 23 is a simple signal that flags periods
of time in which bystanders are likely to be hearing a howl from
the hearing aid 100. In an exemplary embodiment, the analyzer 3 is
further configured to determine a second value indicative of
whether or not the feedback howl detected is potentially inaudible
to the hearing aid user. The second value is optionally used as an
input to the discriminator 4 and/or to the trigger unit 5.
[0058] Operatively connected to the analyzer 3 is a discriminator
(Discriminator) 4 which is configured to create an impact value 24
indicative of whether or not the feedback howl detected persists
over a significant period of time. Input to the discriminator 4 is
the first value 23 determined by the analyzer 3. The impact value
24 is transmitted from the discriminator 4 to a trigger unit
(Trigger unit) 5, which is operatively connected to the
discriminator 4.
[0059] Indicated by the dotted arrow with the numeral 23 is that
the first value 23 can not only be fed to the discriminator 4 for
further calculation, but directly to the trigger unit 5 as well.
Hence, the trigger unit 5 may be configured to trigger a corrective
action considering the first value 23, the second value, and/or the
impact value 24. Further, the trigger unit may terminate a
corrective action, when the howl condition no longer persists
and/or when a user action has been taken. The trigger unit may thus
initiate the return to a normal mode of operation. In an
embodiment, the trigger unit is adapted to activate a feedback
cancellation system, and/or to modify an adaptation rate of an
adaptive algorithm of the feedback cancellation system.
[0060] The hearing aid 100 of FIG. 1 further comprises an
attenuator (Attenuator) 6 operatively coupled to the trigger unit
5. The attenuator 6 is configured, to provide for a second
corrective action, to attenuate the amplified signal 19 presented
to the receiver 10, cf. signal 16, e.g. comprising an attenuation
factor that is to be multiplied onto the amplified signal 19 via
combination unit (`X`). It can also be seen from FIG. 1 that the
hearing aid 100 comprises a signaller (Signaller) 7. The signaller
7 is operatively coupled to the trigger unit 5 as well as to the
receiver 10. Furthermore the signaller is configured to present to
the receiver 10 an electric signal 17 transformable to an acoustic
sound perceivable by the user. In the present embodiment the
electric signal 17 presented to the receiver 10, to provide for a
first corrective action, is a pre-stored warning signal, pre-stored
in the signaller 7. Alternatively, the warning signal may be
generated on demand, e.g. using an on-board speech synthesizer.
Further alternatively, the warning signal may be requested to be
transmitted from an auxiliary device to which a wired or wireless
interface exists.
[0061] If the trigger unit 5 transmits a trigger signal 25--as in
the present embodiment--to both the attenuator 6 and the signaller
7, two corrective actions, namely the first and the second
corrective action, are performed. The control signal 16 originating
from the attenuator 6 attenuates, e.g. mutes, the amplified signal
19 presented to the receiver 10. This results in the howl to
disappear. Secondly a warning signal pre-stored in the signaller 7
is transmitted via transmission line 17 (and combination unit
(`+`), allowing a combination with the possibly attenuated signal
19 of the forward path) to the loudspeaker, informing the hearing
aid user to perform a manual user action.
[0062] When howl is no longer present, the algorithms embodied in
the microphone, 1, the signal processing unit (8, 9), the howl
detector 2, the analyzer 3, the discriminator 4, the trigger 5, the
attenuator 6 and the signaller 7 effect a termination of the
corrective action, such that the hearing aid returns to normal mode
of operation.
[0063] An exemplary flow chart illustrating an embodiment of an
operating method in accordance with the disclosure is depicted in
FIG. 2.
[0064] In a first step (Receive and process acoustic input signal)
110 an acoustic input signal is received and converted into an
electric input signal via a hearing aid's microphone. The electric
signal is processed into a processed signal using an audiological
signal processing unit coupled to the microphone.
[0065] In a second step (Detect howl) 120, the presence of a
feedback howl originating from the hearing aid is detected. The
detection is performed preferably using the processed signal and/or
control signals from the audiological signal processing unit
comprised by the hearing aid.
[0066] In a third step (Estimate audibility of howl) 130 a first
value indicative of whether or not the feedback howl detected is
potentially audible to a person neighbouring the user of the
hearing aid is determined.
[0067] Considering the first value determined in the third step
130, in a fourth step (Perform corrective action) 140 a corrective
action, e.g. attenuating an amplified signal presented to the
receiver, is performed.
[0068] It is to be understood that since the acoustic input signal
picked up by hearing aid's microphone is a continuous signal, the
steps of the operating method can be performed
continuously/repeatedly.
[0069] FIG. 3 schematically shows a hearing aid according to the
present disclosure. The hearing aid (HA) comprises a microphone
(MIC) configured to convert an acoustic input signal to an electric
input signal, a signal processing unit (SP) coupled to the
microphone (MIC) and being configured to process the electric input
signal to a processed signal (including applying a frequency
dependent gain to the electric input signal (or a signal derived
there from) according to a user's needs, e.g. his or her hearing
impairment), and a receiver (loudspeaker, SPK) coupled to the
signal processing unit (SP) and being configured to transform the
processed signal signal into an acoustic output signal. The
microphone (MIC), signal processing unit (SP) and receiver (SPK)
form part of a forward path of the hearing aid. The forward path
may further comprise analogue-to-digital and digital-to-analogue
converters allowing digital signal processing in the forward path
(and possibly elsewhere, e.g. in an analysis path) to be performed.
The signal processing unit (SP) is further adapted for performing
logic actions based on one or more control inputs. The hearing aid
(HA) further comprises a howl detector (HD) coupled to the signal
processing unit (SP) and being configured to detect the presence of
a feedback howl originating from the hearing aid (HA), an analyzer
(ANA) coupled to the howl detector (HD) and being configured to
determine control signal (at least being) indicative of whether or
not the feedback howl detected is potentially audible to a person
neighbouring the user of the hearing aid (HA). The hearing aid (HA)
further comprises a trigger unit (TRU) operatively connected to the
analyzer (ANA) and being configured to trigger a corrective action
considering the control signal from the analyzer. The hearing aid
(HA) further comprises a memory unit (MEM) operatively coupled to
the howl detector (HD), the analyzer (ANA), and the trigger unit
(TRU), thereby allowing said units to store and/or retrieve
information in/from the memory unit (MEM). The memory may e.g. hold
data relating to the user (e.g. an audiogram), a criterion for
deciding whether a detected feedback is audible for a person in the
user's environment, statistical data for the occurrence of howl,
statistical data for the occurrence of speech in the user's
environment, etc. The hearing aid (HA) further comprises an antenna
(ANT) and transceiver unit (Rx-Tx) for establishing a wireless link
to another device, e.g. a second hearing aid of a binaural hearing
aid system or a remote control or another communication device.
Thereby, control signals, information signals and/or audio data
signals may be exchanged between the devices (possibly
one-way).
[0070] The signal processing unit (SP) may be adapted to implement
a corrective action based on inputs from the howl detector (HD),
the analyzer (ANA) and the trigger unit (TRU). Such corrective
action may e.g. be to play a warning message to the user via the
speaker (SPK), where the warning signal is appropriately adapted in
frequency and gain to allow the user to perceive the message
conveyed by the warning signal.
[0071] Preferably, corrective action is only taken when it is
concluded form the available control signals (e.g. from the howl
detector, the analyzer, the trigger unit, data stored in the
memory, etc.) that a feedback howl is present and it is potentially
audible to a person neighbouring the user of the hearing aid. In an
embodiment, corrective action is only taken when it is further
concluded that the detected feedback howl is potentially inaudible
to the hearing aid user (e.g. due to a hearing impairment of the
user). Preferably data reflecting a user's frequency dependent
hearing ability (e.g. hearing loss compared to a normally hearing
person, e.g. an audiogram) are stored in the memory, thereby
allowing a judgement whether a given howl (with a given sound
pressure level and frequency) is audible to the user.
[0072] The hearing aid (HA) may further contain a vibrating element
(VIB) for conveying an information relating to a detected feedback
in the hearing aid to the user (encouraging the user to take action
to reduce such howl, e.g. by reducing volume, improving the
positioning of the hearing aid at the ear of the user, etc.).
[0073] The hearing aid (HA) may further contain other functional
blocks/components than those depicted in FIG. 3, e.g. a feedback
cancellation system. Typically, the hearing aid comprises a local
source of energy, e.g. a battery, e.g. a rechargeable battery, for
energizing some or all of the functional components of the hearing
aid.
* * * * *